microsoft · AArnott · Mar 6, 2026 · Nov 17, 2025 · Nov 17, 2025 · Nov 17, 2025
diff --git a/.config/dotnet-tools.json b/.config/dotnet-tools.json
@@ -10,7 +10,7 @@
       "rollForward": false
     },
     "dotnet-coverage": {
-      "version": "18.1.0",
+      "version": "18.5.2",
       "commands": [
         "dotnet-coverage"
       ],
@@ -24,18 +24,18 @@
       "rollForward": false
     },
     "docfx": {
-      "version": "2.78.4",
+      "version": "2.78.5",
       "commands": [
         "docfx"
       ],
       "rollForward": false
     },
     "nerdbank.dotnetrepotools": {
-      "version": "1.0.92",
+      "version": "1.2.1",
       "commands": [
         "repo"
       ],
       "rollForward": false
     }
   }
-}
+}
diff --git a/.github/Prime-ForCopilot.ps1 b/.github/Prime-ForCopilot.ps1
@@ -0,0 +1,5 @@
+if ((git rev-parse --is-shallow-repository) -eq 'true')
+{
+    Write-Host "Shallow clone detected, disabling NBGV Git engine so the build can succeed."
+    $env:NBGV_GitEngine='Disabled'
+}
diff --git a/.github/actions/publish-artifacts/action.yaml b/.github/actions/publish-artifacts/action.yaml
@@ -14,46 +14,46 @@ runs:
 
   - name: 📢 Upload project.assets.json files
     if: always()
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: projectAssetsJson-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/projectAssetsJson
     continue-on-error: true
   - name: 📢 Upload variables
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: variables-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/Variables
     continue-on-error: true
   - name: 📢 Upload build_logs
     if: always()
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: build_logs-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/build_logs
     continue-on-error: true
   - name: 📢 Upload testResults
     if: always()
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: testResults-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/testResults
     continue-on-error: true
   - name: 📢 Upload coverageResults
     if: always()
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: coverageResults-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/coverageResults
     continue-on-error: true
   - name: 📢 Upload symbols
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: symbols-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/symbols
     continue-on-error: true
   - name: 📢 Upload deployables
-    uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5
+    uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
     with:
       name: deployables-${{ runner.os }}
       path: ${{ runner.temp }}/_artifacts/deployables

diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
@@ -3,7 +3,8 @@
 ## High level guidance
 
 * Review the `CONTRIBUTING.md` file for instructions to build and test the software.
-* Set the `NBGV_GitEngine` environment variable to `Disabled` before running any `dotnet` or `msbuild` commands.
+* Run the `.github\Prime-ForCopilot.ps1` script (once) before running any `dotnet` or `msbuild` commands.
+  If you see any build errors about not finding git objects or a shallow clone, it may be time to run this script again.
 
 ## Software Design
 
@@ -12,9 +13,68 @@
 
 ## Testing
 
-* There should generally be one test project (under the `test` directory) per shipping project (under the `src` directory). Test projects are named after the project being tested with a `.Test` suffix.
-* Tests should use the Xunit testing framework.
-* Some tests are known to be unstable. When running tests, you should skip the unstable ones by running `dotnet test --filter "TestCategory!=FailsInCloudTest"`.
+**IMPORTANT**: This repository uses Microsoft.Testing.Platform (MTP v2) with xunit v3. Traditional `--filter` syntax does NOT work. Use the options below instead.
+
+* There should generally be one test project (under the `test` directory) per shipping project (under the `src` directory). Test projects are named after the project being tested with a `.Tests` suffix.
+* Tests use xunit v3 with Microsoft.Testing.Platform (MTP v2). Traditional VSTest `--filter` syntax does NOT work.
+* Some tests are known to be unstable. When running tests, you should skip the unstable ones by using `-- --filter-not-trait "FailsInCloudTest=true"`.
+
+### Running Tests
+
+**Run all tests**:
+```bash
+dotnet test --no-build -c Release
+```
+
+**Run tests for a specific test project**:
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release
+```
+
+**Run a single test method**:
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release -- --filter-method ClassName.MethodName
+```
+
+**Run all tests in a test class**:
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release -- --filter-class ClassName
+```
+
+**Run tests with wildcard matching** (supports wildcards at beginning and/or end):
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release -- --filter-method "*Pattern*"
+```
+
+**Run tests with a specific trait** (equivalent to category filtering):
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release -- --filter-trait "TraitName=value"
+```
+
+**Exclude tests with a specific trait** (skip unstable tests):
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release -- --filter-not-trait "TestCategory=FailsInCloudTest"
+```
+
+**Run tests for a specific framework only**:
+```bash
+dotnet test --project test/Library.Tests/Library.Tests.csproj --no-build -c Release --framework net9.0
+```
+
+**List all available tests without running them**:
+```bash
+cd test/Library.Tests
+dotnet run --no-build -c Release --framework net9.0 -- --list-tests
+```
+
+**Key points about test filtering with MTP v2 / xunit v3**:
+- Options after `--` are passed to the test runner, not to `dotnet test`
+- Use `--filter-method`, `--filter-class`, `--filter-namespace` for simple filtering
+- Use `--filter-trait` and `--filter-not-trait` for trait-based filtering (replaces `--filter "TestCategory=..."`)
+- Traditional VSTest `--filter` expressions do NOT work
+- Wildcards `*` are supported at the beginning and/or end of filter values
+- Multiple simple filters of the same type use OR logic, different types combine with AND
+- See `--help` for query filter language for advanced scenarios
 
 ## Coding style
 

diff --git a/.github/prompts/template-release-notes.md b/.github/prompts/template-release-notes.md
@@ -0,0 +1,20 @@
+# Template release notes
+
+This file will describe significant changes in Library.Template as they are introduced, especially if they require special consideration when merging updates into existing repos.
+This file is referenced by update-library-template.prompt.md and should remain in place to facilitate future merges, whether done manually or by AI.
+
+## Solution rename
+
+Never leave a Library.slnx file in the repository.
+You might even see one there even though this particular merge didn't bring it in.
+This can be an artifact of having renamed Library.sln to Library.slnx in the template repo, but ultimately the receiving repo should have only one .sln or .slnx file, with a better name than `Library`.
+Delete any `Library.slnx` that you see.
+Migrate an `.sln` in the repo root to `.slnx` using this command:
+
+```ps1
+dotnet solution EXISTING.sln migrate
+```
+
+This will create an EXISTING.slnx file. `git add` that file, then `git rm` the old `.sln` file.
+Sometimes a repo will reference the sln filename in a script or doc somewhere.
+Search the repo for such references and update them to the slnx file.
diff --git a/.github/prompts/update-library-template.prompt.md b/.github/prompts/update-library-template.prompt.md
@@ -0,0 +1,65 @@
+---
+description: Merges the latest Library.Template into this repo (at position of HEAD) and resolves conflicts.
+---
+
+# Instructions
+
+1. Run `tools/MergeFrom-Template.ps1`
+2. Resolve merge conflicts, taking into account conflict resolution policy below.
+3. Validate the changes, as described in the validation section below.
+4. Committing your changes (if applicable).
+
+## Conflict resolution policy
+
+There may be special notes in `.github/prompts/template-release-notes.md` that describe special considerations for certain files or scenarios to help you resolve conflicts appropriately.
+Always refer to that file before proceeding.
+In particular, focus on the *incoming* part of the file, since it represents the changes from the Library.Template that you are merging into your repo.
+
+Also consider that some repos choose to reject certain Library.Template patterns.
+For example the template uses MTPv2 for test projects, but a repo might have chosen not to adopt that.
+When resolving merge conflicts, consider whether it looks like the relevant code file is older than it should be given the changes the template is bringing in.
+Ask the user when in doubt as to whether the conflict should be resolved in favor of 'catching up' with the template or keeping the current changes.
+
+Use #runSubagent to analyze and resolve merge conflicts across files in parallel.
+
+### Keep Current files
+
+Conflicts in the following files should always be resolved by keeping the current version (i.e. discard incoming changes):
+
+* README.md
+
+### Deleted files
+
+Very typically, when the incoming change is to a file that was deleted locally, the correct resolution is to re-delete the file.
+
+In some cases however, the deleted file may have incoming changes that should be applied to other files.
+The `test/Library.Tests/Library.Tests.csproj` file is very typical of this.
+Changes to this file should very typically be applied to any and all test projects in the repo.
+You are responsible for doing this in addition to re-deleting this template file.
+
+## Validation
+
+Validate the merge result (after resolving any conflicts, if applicable).
+Use #runSubagent for each step.
+
+1. Verify that `dotnet restore` succeeds. Fix any issues that come up.
+2. Verify that `dotnet build` succeeds.
+3. Verify that tests succeed by running `tools/dotnet-test-cloud.ps1`.
+
+While these validations are described using `dotnet` CLI commands, some repos require using full msbuild.exe.
+You can detect this by checking the `azure-pipelines/dotnet.yml` or `.github/workflows/build.yml` files for use of one or the other tool.
+
+You are *not* responsible for fixing issues that the merge did not cause.
+If validation fails for reasons that seem unrelated to the changes brought in by the merge, advise the user and ask how they'd like you to proceed.
+That said, sometimes merges will bring in SDK or dependency updates that can cause breaks in seemingly unrelated areas.
+In such cases, you should investigate and solve the issues as needed.
+
+## Committing your changes
+
+If you have to make any changes for validations to pass, consider whether they qualify as a bad merge conflict resolution or more of a novel change that you're making to work with the Library.Template update.
+Merge conflict resolution fixes ideally get amended into the merge commit, while novel changes would go into a novel commit after the merge commit.
+
+Always author your commits using `git commit --author "🤖 Copilot <no-reply@github.com>"` (and possibly other parameters).
+Describe the nature of the merge conflicts you encountered and how you resolved them in your commit message.
+
+Later, if asked to review pull request validation breaks, always author a fresh commit with each fix that you push, unless the user directs you to do otherwise.
diff --git a/.github/workflows/copilot-setup-steps.yml b/.github/workflows/copilot-setup-steps.yml
@@ -26,7 +26,7 @@ jobs:
     # You can define any steps you want, and they will run before the agent starts.
     # If you do not check out your code, Copilot will do this for you.
     steps:
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
     - name: ⚙ Install prerequisites

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
@@ -24,7 +24,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
     - name: ⚙ Install prerequisites
@@ -40,4 +40,4 @@ jobs:
 
     - name: Deploy to GitHub Pages
       id: deployment
-      uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4
+      uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4.0.5
diff --git a/.github/workflows/docs_validate.yml b/.github/workflows/docs_validate.yml
@@ -13,11 +13,11 @@ jobs:
     name: 📚 Doc validation
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
     - name: 🔗 Markup Link Checker (mlc)
-      uses: becheran/mlc@18a06b3aa2901ca197de59c8b0b1f54fdba6b3fa # v1.0.0
+      uses: becheran/mlc@7ec24825cefe0c9c8c6bac48430e1f69e3ec356e # v1.2.0
       with:
         args: --do-not-warn-for-redirect-to https://learn.microsoft.com*,https://dotnet.microsoft.com/*,https://dev.azure.com/*,https://app.codecov.io/* -p docfx -i https://aka.ms/onboardsupport,https://aka.ms/spot,https://msrc.microsoft.com/*,https://www.microsoft.com/msrc*,https://microsoft.com/msrc*,https://www.npmjs.com/package/*,https://get.dot.net/,https://dev.azure.com/devdiv/*
     - name: ⚙ Install prerequisites

diff --git a/.github/workflows/libtemplate-update.yml b/.github/workflows/libtemplate-update.yml
@@ -17,7 +17,7 @@ jobs:
       contents: write
       pull-requests: write
     steps:
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
 

diff --git a/Directory.Packages.props b/Directory.Packages.props
@@ -4,29 +4,34 @@
   <PropertyGroup>
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
     <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
+    <MicrosoftTestingPlatformVersion>2.1.0</MicrosoftTestingPlatformVersion>
 
     <MicroBuildVersion>2.0.208</MicroBuildVersion>
   </PropertyGroup>
   <ItemGroup>
     <PackageVersion Include="MessagePack" Version="2.5.198" />
-    <PackageVersion Include="Microsoft.VisualStudio.Composition" Version="17.12.20" />
-    <PackageVersion Include="Microsoft.VisualStudio.Interop" Version="17.13.40008" />
-    <PackageVersion Include="Microsoft.VisualStudio.SDK.Analyzers" Version="17.7.47" />
-    <PackageVersion Include="Microsoft.VisualStudio.Shell.15.0" Version="17.13.40008" />
-    <PackageVersion Include="Microsoft.VisualStudio.Utilities" Version="17.13.40008" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageVersion Include="Microsoft.VisualStudio.Composition" Version="17.13.41" />
+    <PackageVersion Include="Microsoft.VisualStudio.Interop" Version="17.14.40260" />
+    <PackageVersion Include="Microsoft.VisualStudio.SDK.Analyzers" Version="17.7.79" />
+    <PackageVersion Include="Microsoft.VisualStudio.Shell.15.0" Version="17.14.40264" />
+    <PackageVersion Include="Microsoft.VisualStudio.Utilities" Version="17.14.40264" />
     <PackageVersion Include="Microsoft.ServiceHub.Framework.Testing" Version="4.8.55" />
     <PackageVersion Include="NSubstitute" Version="5.3.0" />
     <PackageVersion Include="System.ComponentModel.Composition" Version="9.0.13" />
-    <PackageVersion Include="Xunit.SkippableFact" Version="1.5.23" />
+    <PackageVersion Include="Xunit.SkippableFact" Version="1.5.61" />
     <PackageVersion Include="xunit" Version="2.9.3" />
-    <PackageVersion Include="xunit.v3.assert" Version="3.2.0" />
-    <PackageVersion Include="xunit.v3.extensibility.core" Version="3.2.0" />
+    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
+    <PackageVersion Include="xunit.v3.assert" Version="3.2.2" />
+    <PackageVersion Include="xunit.v3.extensibility.core" Version="3.2.2" />
   </ItemGroup>
   <ItemGroup Label="Library.Template">
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.5.2" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CrashDump" Version="$(MicrosoftTestingPlatformVersion)" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.HangDump" Version="$(MicrosoftTestingPlatformVersion)" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.TrxReport" Version="$(MicrosoftTestingPlatformVersion)" />
     <PackageVersion Include="Microsoft.VisualStudio.Internal.MicroBuild.NonShipping" Version="$(MicroBuildVersion)" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
-    <PackageVersion Include="xunit.v3" Version="3.2.0" />
+    <PackageVersion Include="xunit.v3.mtp-v2" Version="3.2.2" />
   </ItemGroup>
   <ItemGroup>
     <!-- Put repo-specific GlobalPackageReference items in this group. -->

diff --git a/azure-pipelines/BuildStageVariables.yml b/azure-pipelines/BuildStageVariables.yml
@@ -2,4 +2,3 @@ variables:
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
   BuildConfiguration: Release
   NUGET_PACKAGES: $(Agent.TempDirectory)/.nuget/packages/
-  # codecov_token: 4dc9e7e2-6b01-4932-a180-847b52b43d35 # Get a new one from https://codecov.io/
diff --git a/azure-pipelines/Merge-CodeCoverage.ps1 b/azure-pipelines/Merge-CodeCoverage.ps1
@@ -28,6 +28,7 @@ try {
     if ($reports) {
         $reports |% { $_.FullName } |% {
             # In addition to replacing {reporoot}, we also normalize on one kind of slash so that the report aggregates data for a file whether data was collected on Windows or not.
+            Write-Verbose "Processing $_"
             $xml = [xml](Get-Content -LiteralPath $_)
             $xml.coverage.packages.package.classes.class |? { $_.filename} |% {
                 $_.filename = $_.filename.Replace('{reporoot}', $RepoRoot).Replace([IO.Path]::AltDirectorySeparatorChar, [IO.Path]::DirectorySeparatorChar)